Sure, I've rebuilt a couple Carter WOs. I follow the initial instructions for the first start up, but I'm not sure where to go from there.
I generally set the idle to where it 'sounds' good. (That being, the engine runs smooth at the lowest rpm without stalling or struggling from lack of fuel)
With the idle mixture screw at 1.5 turns out, I'll change it to 1 3/4 out, but I don't know what I'm accomplishing when I do this. The idle sounds like it increases, so I think I can turn the idle back down, so I do.
I guess I just would like to know what is happening when I make idle mixture adjustments...and how I can get the most efficient settings for my geography.
What you are adjusting to is as close to the perfect idle setting your motors' systems will allow. With an engine that is fully warmed up. With a vacuum Gauge and a Dwell/Tachometer hooked up. You're looking to have a carb that functions, first and foremost without choke. This is as near to a balanced fuel/air mixture as can be had without the fine tuning. The back end of my post on "Setting the Timing Without a Light" outlines the procedure you will use. You will find it under "Tools". But suffice to say if your timing is right all you need to do is adjust the Steel Idle Stop Screw to either open or close the throttle plate enough to get the perfect gap between the edge of the plate and the idle port, as seen at the bottom of the diagram, such that a perfect vacuum is pulling enough or more fuel to match the air flow. You will check this with the Vacuum Gauge. The higher the reading, up to 21 inHg, the better. If it doesn't come into range, you have either a vacuum leak or poor valve timing. Now that that is set, you need to set the mixture screw for the best idle as indicated on the Dwell/Tach. You are going to adjust the mixture toward lean and as you reach the point where the motor begins to stumble, enrich it a 1/4 turn. Your idle should be showing as between 600 and 700, maybe little lower or higher, depending on wear in the throttle. At any rate 600-700 is the correct range. NOTE: Generator-equipped motors need 700 RPM for the Genny to become active and charge. I hope this helps.
Over the years of tuning my toys, I've learned you need some basic things on all engines before it will adjust to a nice idle. You first need a engine that is in spec. Good even compression with a ignition system that is firing at the right time and not leaking spark anywhere. Valve clearance must be correct. Then you need a carburator that is clean, and adjusted internally , such as float setting and correct jets or needles for your particular altitude. Vacuum leaks on the intake or carburator will nix your settings. This can be a daunting task. A shop manual that pertains to each model or make is your best friend. Try and put the machine in the condition the manual recommends. You will fight a losing battle if you don't. Listen to your engine. The sounds it makes will tell you much. A Jeep will fight the starter if it's too far advanced in timing. Starting a engine from scratch that you have never run is a challenge. You need to set the basics in a very close to correct form, or you are in for a battle. Static timing, gaps, seals, basic carburator screw settings, all must be close before it will start. If you hear a back fire, you have the timing or plug wiring off. Did it bang in the exhaust, or up through the carburator? Listening to these signs will lead you in the right direction. It takes very little movement of the distributor and your Jeep won't start. Each model of carburator has it's own set of rules of engaugement. Sounds like a war doesn't it? It sometimes is. Fighting and winning is a rewarding experience. It's a pleasure when it works as intended. What Our Scout does, is get your carburator in true form so that part of the battle is over with for you! A fine service. If you learn to hold your mouth just right, she will purr for you. It's rare to have so many people interested in a vehicle type, available to help you succeed. Jeeps are simply amazing. I'm glad to share and help if I can. Many have already helped me. Pass it on! John
Thank you for the response. It makes more sense to me now. I think I need to get a couple tools...Dwell, vacuum gauge, etc...
While working through other issues...(Balancing a flywheel), I fired up the engine. Carter WO, fresh rebuild, ran fine before pulling the TC/Tranny 2 weeks ago. The Carter no longer idles. It throttles up fine. I checked for vacuum leaks with Propane. (No leaks)
I am feeding the running chassis from an old gas can. I think I got some crud in the idle passage, but I'm not sure where to look or what to clean. Can you point me in the right direction?
Edit: Oh, and if I hold the choke plate closed a bit, it idles.
Last Edit: Jan 15, 2015 12:57:51 GMT -5 by athawk11
Rick, I'm about to toss this damn thing in the trash. If you weren't so backed up, it would already be heading your way.
All Jets and passages have been cleaned per your instruction. I added a fuel filter. Still won't idle...at all...without holding the choke closed. High speed works fine.
I remember reading in one of your excerpts that you want to see a strong squirt of fuel in the venturi when pressing pedal for fuel. I see nothing. No squirts.
Edit: Oh, While apart, I replaced the linkage you sent me. Thank you. I also rechecked the float level, adjusted the fuel plunger linkage, and replaced the needle. It is now the Viton style. (I was having some dripping out the throttle shaft after shut down)
Last Edit: Jan 17, 2015 14:23:05 GMT -5 by athawk11
Post by Scoutpilot on Jan 17, 2015 18:02:29 GMT -5
Have you inspected the float tang (contacts the needle) for gouges, scrapes or cuts? If you find a divot there, use 800 Wet or Dry to buff it out. Inspect the float pin for grooves. Grooves will alter the float setting as it moves. Check the tower the pin slides through to hold the float. If the holes are out of round or sloppy big, that too, will mess with the float setting. Do this, reinstall and recheck the float at 3/8" after. Beyond that, you have a throttle shaft/bore problem. Wobbly shaft, vacuum leak.
Float, pin and tower all appear to be in decent condition. Tang was polished to baby butt smooth. I read all the way through the 2A Page thread and paid careful attention to this and other instructions.
The throttle shaft seems tight. I checked it again when I replaced the throttle linkage.
The thing that is so disturbing...this Carter was performing flawlessly after my rebuild and for the five following months, up until I didn't run the Jeep for a couple weeks while repairing the flywheel.
As a test, I took a good running Carter off my 2A and installed it on this 3A. It idles and accelerates perfectly. It didn't even need any choke for warm up.
This eliminates electrical, timing and fuel delivery issues...and most vacuum issues. The throttle shaft could be leaky, but it would have had to go crappy while sitting dormant for 2 weeks. Am I back to checking the cleanliness, float and settings?